Marine biofouling is the build up of microbial slimes, plants and animals on any surface immersed in seawater. Biofouling adds to the operational costs of shipping throughout the world. The additional drag on marine vessels caused by biofouling significantly increases operating and maintenance costs. For example, biofouling can raise fuel consumption by as much as 30%. Because many traditional antifouling coatings containing metal-derived biocides have been linked to harmful effects on non-target organisms, environmentally friendly alternatives are being sought.
Antifouling paints containing tin and copper biocides are currently used because they are effective against most forms of marine fouling. Many of these biocidal organometallic compounds are environmentally persistent. They can cause damage to the ecosystem and enter the food chain. Most countries around the world are adopting measures to limit or ban the presence of tributyltin antifoulants on vessel hulls, and copper-based coatings are expected to face similar restrictions in the near future.
Non-toxic “fouling-release” or “fouling-repellant” coatings are one class of alternatives to biocidal coatings. Silicone-based paints are commercially available, but may not satisfy many desired performance characteristics. The soft silicones, as well as many other commercially available coating systems, lack the toughness required to withstand the rigorous demands of the marine environment, do not sufficiently and consistently self-clean, or, due to polymer restructuring or other degradation pathways, lose many of the desirable surface properties with time and exposure to marine organisms.
Accordingly, materials that lower the strength of adhesion between fouling organisms and a surface, for example, a marine surface, are currently sought by governments and industries involved in shipping. A surface that is resistant to marine biofouling, for example, fouling by marine organisms such as zoospores and diatoms (unicellular algae), is also sought. The diversity of fouling organisms and environmental conditions worldwide makes developing a coating that resists fouling a challenging task. Thus, novel non-toxic solutions to the problems of biofouling are needed.